ET ATTACK_RESPONSE Observed AsyncRat Installer Inbound

Query · suricata

flow:established,to_client;
http.content_type;
content:"application/x-msdownload";
http.header;
content:"content|2d|disposition|3a 20|attachment|3b 20|filename|3d|asyncclient|2e|exe"; nocase; fast_pattern;
content:"cloudflare.com"; nocase;
http.response_body;
content:"|4D 5A|"; startswith;
target:dest_ip;
Raw source ET ATTACK_RESPONSE Observed AsyncRat Installer Inbound · Suricata
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Published by Emerging Threats Open ↗, licensed under BSD 3-Clause ↗. Line breaks added for readability; the rule is otherwise unchanged. 
alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"ET ATTACK_RESPONSE Observed AsyncRat Installer Inbound";
    flow:established,to_client;
    http.content_type;
    content:"application/x-msdownload";
    http.header;
    content:"content|2d|disposition|3a 20|attachment|3b 20|filename|3d|asyncclient|2e|exe"; nocase; fast_pattern;
    content:"cloudflare.com"; nocase;
    http.response_body;
    content:"|4D 5A|"; startswith;
    classtype:trojan-activity;
    sid:2064060; rev:1;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, tls_state TLSDecrypt, created_at 2025_08_20, deployment Perimeter, deployment SSLDecrypt, malware_family AsyncRAT, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_08_20, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1105, mitre_technique_name Ingress_Tool_Transfer;
    target:dest_ip;
)

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